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log file sync

DBAs,

We recently got a lot of complaints about one database for its slowness.
I took a snapshot during the slow time whose time window is 15 minuets.
From the stats report, in the top 5 waits, we saw the log file sync.
How can we know it is abnormal or normal?

Two. You might be keeping other datafiles or temp files in the redo log area. Move redo to a separate device. Do not keep them in RAID 5.

Three. See the log file size, if frequent switches are there increase the size.

I also face frequent log switches in one of my db with solaris 8,
might be the undo the reason for the redo fast filling.

Your points 1.) and 3.) have nothing to do with log file sync wait event.

What the original poster realy need to check is if there realy is the need for apparent high commit rate. The most likely reason for log file sync event is when user issues a commit (or rollback). So he/she need to check who (or what) is causing frequent commits.

Jurij ModicASCII a stupid question, get a stupid ANSI
24 hours in a day .... 24 beer in a case .... coincidence?

Your points 1.) and 3.) have nothing to do with log file sync wait event.

Point 1 may help - by reducing the buffer size you increase the chance that the log writer will asynchronously write to the log file without the session having to wait on a log file sync. Now if the transactions are very small then this is going to be of limited help, but it likewise is unlikely to do harm.